WASHINGTON (Reuters) - Republicans in the U.S. Congress who are pushing for action on immigration legislation said on Thursday they were getting closer to an agreement on a bill that President Donald Trump could support.

"I think we've had better discussions in the last 48 hours than in the last 48 months," said Representative Mark Meadows, chairman of the hard-right House Freedom Caucus.

Meadows was referring to negotiations with both the White House and centrist House Republicans on a bill that would address the future of young immigrants known as "Dreamers" who were brought to the United States illegally when they were children.

But Meadows also said details had to be worked out on difficult issues before a bill could be ready for House floor debate.

Meadows, Trump and many House conservatives are pushing for tough new controls on legal and illegal immigration that Democrats and some moderate Republicans oppose.

Fearing defeat in November congressional elections and possibly their control of the House of Representatives, conservatives want to demonstrate to their voter base that they have been pushing forward on Trump's demands to clamp down on immigration.

Meadows and other Freedom Caucus members on Thursday even threatened to bring down a massive farm bill being pushed by their leaders if an immigration debate is not held first.

Republican Representative Jeff Denham, who is threatening to use procedural tactics to force a wide-ranging debate on the House floor, said on Thursday he thought negotiators could fashion legislation that both hardline conservatives and Democrats could support.

Denham has been behind a bipartisan immigration bill that falls far short of what Meadows' group has been advocating.

“We are now having a discussion about the principles the president put out and which ones get bipartisan support,” Denham said.

In remarks to reporters, Meadows warned that simply swapping protections for the "Dreamers" in return for $25 billion to build Trump's southwest border wall "will never happen" because it would not go far enough for the president, who also wants to cut legal immigration significantly.

"It sounds to me like they're trying to keep a productive process from occurring," she said in a hallway interview, adding that House Republicans have had since last September to craft an immigration bill. That was when Trump said he was ending a program to help the "Dreamers," which former Democratic President Barack Obama created in 2012.